AP stats unit 1

population

the entire group in a statistical study we want info from.

sample

a subset of individuals in the population who we get data from.

SRS

Simple random sample: a size of n is chosen in a way that every group of n individuals in the population has equal chance to be selected as the sample.

convenience sample

selecting individuals from the population who are easy to reach.

bias

likley to overestimate or underestimate the value wanted

voluntary response

individuals choose to be in the sample via general invitation.

strata

individuals in a populations who share characteristics associaated with the variable being tested

stratified random sample

split the population into groups (strata) and choose srs from each group.

cluster

individuals in a population who are LOCATED near eachother

cluster sampling

split population into clusters based on location, randomly select groups, then survey everyone in the selected groups.

to obtain an srs…

we do an lrs!!!

LRS

label, randomize, specify

response bias

problems in the data gathering process (wording, appearance, process)

undercoverage

when members of the population cannot/be less likely to be included in a sample

non-response

when an individual is part of a sample but chooses not to respond or can't be reached.

explanatory variable

Independent variable, can influence, explain, or predict changes in response variable.

response variable

dependent variable, being measured or predicted.

Observational Study

Observes individuals and measures variables of intrest but does not attempt fo influence responses (no treatment)

experiment

controlled procedure where variables are manipulates to find a relationship between variables (cause and effect).

experimental unit

objects/individuals used in an experiment

treatment

a specific condition/intervention applied to experimental units.

comparison

2 or more treatments

for random assignment…

LRS!

replication

repeating a study multiple times for accuracy.

random sample

apply to larger population

random assignment

cause and effect

statistically signifigant

observed results of a study are too unusual to be explained by change alone.

block

EXPERIMENT, group of experimental units that are known to be similar.

under/overreporting

cause bias conclusions because if a study is self reporting, the sample might report inaccurate data.